我再也无法确定从我的任何蓝牙设备上按下了什么按钮。
GetParcelableExtra为MEDIA_BUTTON Intent回调中的KEY_EVENT返回空值。
这个方法工作了几个月，但突然开始在GetParcableExtra上返回null。
我怎样才能从xamarin的后台服务中获取蓝牙按钮事件？

namespace foo
    {
        [Service]
        class BackgroundService : Service
        {
            [return: GeneratedEnum]
            public override StartCommandResult OnStartCommand(Intent intent, [GeneratedEnum] StartCommandFlags flags, int startId)
            {
                registerMediaButtons();
                
                return StartCommandResult.Sticky;
            }

        private void registerMediaButtons()
        {
            var am = (AudioManager)this.GetSystemService(AudioService);
            var componentName = new ComponentName(PackageName, new MyMediaButtonBroadcastReceiver().ComponentName);
            #pragma warning disable CS0618 // Type or member is obsolete
            am.UnregisterMediaButtonEventReceiver(componentName);
            am.RegisterMediaButtonEventReceiver(componentName);
            #pragma warning restore CS0618 // Type or member is obsolete
        }

        [BroadcastReceiver]
        [IntentFilter(new[] { Intent.ActionMediaButton, Intent.ActionHeadsetPlug, AudioManager.ActionAudioBecomingNoisy })]
        public class MyMediaButtonBroadcastReceiver : BroadcastReceiver
        {
            public string ComponentName { get { return Class.Name; } }

            public override void OnReceive(Context context, Intent intent)
            {
                if (intent.Action == Intent.ActionMediaButton)
                {
                    var keyEvent = (KeyEvent)intent.GetParcelableExtra(Intent.ExtraKeyEvent);

                    if (keyEvent == null)// always null now
                        return;

                    if (keyEvent.KeyCode == Keycode.Headsethook)
                    {
                        if (keyEvent.Action == KeyEventActions.Down)
                        {
                            
                        }
                    }
                }
            }
        }
    }
}